Meaningful dual-polarized radar estimations suitable for radar meteorology require a cross-polarization discrimination (XPD) and isolation (XPI) in excess of 30 dB to reach a differential reflectivity accuracy lower than 0.1 dB. A planar dual-polarized patch antenna array featuring low cross-polarization is proposed to meet these requirements via a simple implementation of imaged feeding and candidates as a cost-effective electronically steerable array for short-range X-band weather radars.
However, relatively high levels of cross-polarization are to be expected in a patch array and therefore counteracted with specific designs. To this end, a feed rotation technique is implemented via bi-axial imaging of the feeding probes for each logical sub-array of 2 by 2 elements. Improvements in XPD respect to a repeated feeding scheme are significant and in excess of 30 dB. Based on successful designs and simulations in CST Microwave Studio and ANSYS HFSS, an X-band array of 4 by 4 patches has been manufactured. Extensive instrumental validation has been largely supporting this specialized feeding concept meeting the theoretical expectations and electromagnetic simulation results.